Recently proposed window glass panes or sheets for use on such vehicles as automobiles include a light-adjusting panel structure for electrically adjusting an external light by applying voltage to a light-adjusting element housed in the light-adjusting panel structure.
The light-adjusting panel structure comprises a pair of glass panes each having an intermediate film laminated on opposed surfaces and a light-adjusting element laminated between the intermediate films via an electrode layer. A light-adjusting sheet is provided by laminating the pair of electrode layers and the light-adjusting element. End part of the light-adjusting sheet covered with a tape-form film so as to have a substantially U-shaped cross section.
By covering the end part with the tape-form film, entry of a plasticizer contained in the intermediate films can be prevented from entering the light-adjusting element. By prevention f entry of the plasticizer into the light-adjusting element, it is possible to prevent function deterioration by the plasticizer of the light-adjusting element. As the light-adjusting element, a liquid crystal, a Suspended Particle Device (SPD) may be adopted (see Patent Literature 1).
In the light-adjusting panel structure of Patent Literature 1, however, because the end part of the light adjusting sheet is covered by the tape-form film into a U-shaped cross-section, the tape-form film is stuck along a peripheral edge part (front surface). Thus, the opposite ends of the tape-form film bonded along the peripheral edge of the light-adjusting sheet can be seen from outside, whereby the aesthetic appearance of the panel structure may be injured.
Further, since only the end part of the light-adjusting sheet is covered by the tape-form film, the pair of glass panes laminated on both surfaces of the light-adjusting sheet is not covered by the tape-form film. Thus, the pair of glass panes is bonded to both surfaces of the light-adjusting sheet vi the intermediate film only. Hence, as a load acted on the glass panes in a direction of peel from the light-adjusting sheet, the acted load must be borne or supported by the light-adjusting sheet alone. But the support may not be sufficient.
In one known light-adjusting panel structure, a glass sheet is bonded to each of opposite surfaces of a light-adjusting sheet via an adhesive such that the end surfaces of the light-adjusting sheet, adhesive and the glass panes are formed flat and covered with a seal material. Specifically, the entire areas of the end parts of the light-adjusting sheet, the adhesive and the glass panes (namely, only the end surface of the light-adjusting panel structure) are coated with the seal material (see, e.g., Patent Literature 2).
By coating the entire end surfaces of the light-adjusting sheet, the adhesive and the glass panes with the seal material, the plasticizer contained in the adhesive can be prevented from entering the light-adjusting element. By coating the seal material only to the end surface of the light-adjusting panel structure, there is no fear of the seal material being seen from outside. Note also that, by coating the seal material to each entire end surface of the light-adjusting sheet, the adhesive and the glass panes, it is possible to bear with the adhesive a load acted in a direction to tear the glass panes off from the light-adjusting sheet.
However, in the light-adjusting panel structure of Patent Literature 2, the seal material is applied to the end surface of the light-adjusting sheet (namely, light-adjusting element). Thus, there is a fear that a plasticizer contained in the seal material will enter the light-adjusting element. Note also that since each end surface of the adhesive and the glass sheets is formed flat, the end surfaces of the adhesive and the glass sheets are disposed closely to each other. Thus, when a gap arises between the end surface of the light-adjusting sheet and the seal material, the plasticizer contained in the adhesive is liable to enter the light-adjusting element.